1. Field of the Invention
The present invention relates to an organic light-emitting device having an organic light-emitting element covered with a covering member, and a method for manufacturing the organic light-emitting device.
2. Description of the Related Art
In a normal organic light-emitting device, an organic light-emitting element (organic electroluminescence element) is covered with a covering member such as glass, a metal, a resin and a polarizing plate, in order to prevent the organic light-emitting element from deteriorating affected by water or oxygen.
In the case of an organic electroluminescence element having a gel layer as an intermediate layer in the upper part, a technology is known which dampproofs the organic electroluminescence element, by placing an adhesive on a perimeter of a flat covering glass plate after bringing the flat covering glass plate as a covering member in close contact with and on the intermediate layer (U.S. Pat. No. 5,194,027).
Another technology is known which double-dampproofs an organic electroluminescence element with the use of a hollow structure obtained by etching a glass sealing plate, applying an adhesive onto the back face, bonding the above described glass sealing plate as a covering member to a substrate to seal the inner part, and then placing an adhesive again at the joined perimeter of the glass sealing plate (Japanese Patent Application Laid-Open No. 2000-208251). Further, an organic electroluminescence panel is known in which a notch with a chamfered corner is formed on a sealing glass plate for sealing the organic electroluminescence element so as not to damage a flexible wiring board to be placed thereon (Japanese Patent Application Laid-Open No. 2004-234938).
Organic electroluminescence display devices according to U.S. Pat. No. 5,194,027 and Japanese Patent Application Laid-Open No. 2000-208251 have a problem that a perimeter of the covering member is damaged or partially peeled off from a periphery thereof by a large external peeling force that acts on a corner of the covering member, which is caused by a water pressure in a cleaning step or a physical impact force after an organic electroluminescence element is covered with the covering member.
Furthermore, in a step of placing an adhesive on a perimeter of a covering member, an appropriate very small amount of the adhesive must be placed at a correct position to bond and fix the covering member to the substrate. For example, the organic electroluminescence display devices also have a problem that the step of applying a large amount of the adhesive to the perimeter of the covering member and then removing an excessive adhesive with a squeegee leads to a high material cost and a high apparatus cost.
When applying an adhesive to a perimeter of a covering member with a high accuracy by using a dispenser, it is necessary, for instance, to set a dispenser needle diagonally to the perimeter so that the dispenser needle may not contact with the covering member. Consequently the organic electroluminescence display devices further have a problem that a robot-moving mechanism becomes complicated in order to adjust an angle of the dispenser needle and rotate the dispenser needle, whereby an apparatus cost increases.